Alkylation of aromatic hydrocarbons



PatentedApr. 24, 19:45 t l ALKr A'rloN or anoma'rlo HYDRU- cannons Vladimir N. Ipatiefi and Louis Schmerling, Riverside, ill, assisnors to Universal ml Products Company, Chicago, lib, a. corporation of Delaware Application May 13, was, Serial No. tastes 14 Claims. (oi. zet -en) I This is a continuation-in-part of our cmpend- It is oneobject of the present invention to pro ilng application Serial No. 443,398 filed May 18, vide an improved process for the production 01].

1942, which in turn is a continuaticn ln-part of ailiyl aromatics fremaromatics and aliphatic a1- our application Serial No. 430,495, filed February cohols. Another object of the present invention 11,1942. v is to overcome the inherent disadvantages re- I'his'invention relates to the production of alsulting from incomplete conversion to ethylbenhyl aromatics from aromatic hydrocarbons and zenes when benzene is alkylated with ethyl alalcohols. It is specifically concerned with the 'cohol. A still further object of this invention production of monoethylbenzene from benzene is to provide a unitary y m r the e y and ethyl alcohol. i tion of ethyl alcohol and the alkylation of hen- Aromatic hydrocarbons such as benzene are zene with the re ul a y fi,

readily allzylated with olefinlc hydrocarbons, e. g., In one broad aspect the inventionsomprises ethylene, propylene, butylene, etc. in the press dehydratin n alc o in e P fin Of l I ence of a variety of alkylation catalysts. One ky i n n C n ini n l yl ins and process-which .ls of particular importanc m. hydrating catalyst, dissolving the resultant olefin prises the production of monoethylbenzene by in an aromatic hydrocarbon, and introducing said the alkylation of benzene with ethylene using a solution to another portion of said zone wherein solid phosphoric acid catalyst. Other alkylating the aromatic hydrocarbonis alkylated with said catalysts may also be employed such as certain efi of the metal phosphates, silica-alumina comn 0116 Specific embodiment e ve t on 0 posites, and various silicafcontainlng natural p e a P o for t Dmdubtifln 0f molwethyb clays and earths. These catalysts are not necesbenzene which Comprises introducing e ylene sarlly equivalent in their effectiveness, however, and a molar EXCESS of benzene i to the nl t end since difierent operating conditions may be necof n k a n o c ntainin an alkylat s essarydependem; upon th particula catalyst and dehydrating catalyst and therein :alkylating and reactants em loyed. It is also possible to. d nz ne with said ethylene, int odu produce monoethylbenzene by reacting benzene ethyl c hol mtojsaid zone at a point te medk and, ethyl alcohol in the presence of an alkylaate the inlet and outlet thereof and therein det on catalyst nder suitable conditions or teznhydrating Said alcohol to formethylene and Weperature and. pressure. Many of the catalysts Withdrawing the reaction mixture from the useful ior'the alkylation of aromatics such as Outlet 'el d of d Z0119, fractionating d xtho'se hereinbefore. specified, possess dehydratture to separate aikylatien productsaiid an uninzprcperties, and apparently when they are used converted benzene fraction containing dissolved thelreactiontor benzene with ethyl alcohol roethylene, n-lcoveriml said al svlation pr d cts, and ceeds by way of preliminary dehydration of the, 35 ecyclingsfi i 80111191011 of ethylene n enzene to alcohol to ethylene which then reacts. with the the inlet of ztfifa benzene. v I Although the invention broadly contemplates ene are onta t d und alkyla ting conditions the preferred catalysts are those containing phoswith an alkylating and dehydrating catalyst ;40 phoric acid which may constitute 80% or more such as the solidphcsphoric acid catalyst the b i f the catalyst material and'in most ethylene is substantially completely converted to 68595118 not s than 0% y Weight thereot It has been found that when benzene ethylthe use of an alkylating and dehydrating catalyst, 2

alkyl benzenes in agslngle pass through the're- 0f the various acids of homs, ortho or action zone leaving only arelatively small quan- PY 'QP Ph rIc acids are'generally preferred, al tity of unreacted ethylene to be recycledl'n the r 1111 8 the invention is n e ted to their process. 'However, when ethyialcoholjs emusdbut may employ catalyst compositestormed Y ployed as the alkylating agent, experimental tests from the other catalytically e cids have shown that substantially complete deh of'phesphorusreerflcularly 5 in c phoss dration ofthe alcohol is obtained on a sin phorus has a valenceot The acids or. ho pass through the catalyst zone but a very sub-- P P which may be employed will equivga propqrflon of the ethylene thus produced alent in-their activity andtlie'a-ctivity of the final remains unconverted. '.'I'hiS fact necessitates the fiatanlytic mixture is also pendent upon the ratio recycle o! relatively large quantitiesof ethylene 0f acid other comppnenfs Present thereinto the alkylatlon zone in order to obtain com- A particularly Preferred lyst is the so plete utillzation'oi the available ethylene.- so a l d solid phosphoric acid catalyst comp s ns a calcined composite of a catalytically active acid as diatomaceous earth, to form a rather wet paste (the acid ordinarily being in major proportion by weight); calcining at temperatures of about 750 F. to about 950 F. to produce a solid cake; grinding and sizing to produce particles of usable mesh; and dehydrating the catalyst granules at temperatures of between about 400 F. and about 600 F., and preferably at about 500 F., to produce an acid. composition corresponding to the optimum alkylating activity. The catalyst preparation procedure may be varied by forming par-- ticles of the original paste by extrusion or by pelleting methods, followed by calcination and rehydration.

Alkylation of benzene by ethylene is effected in the presence of a solid phosphoric acid catalyst at temperatures of between about 400 F. and

about 850 F. and preferably of about 500 F. to about 575 F. and at pressures of between about 300 and about 2000 pounds and preferably of between about 600 and about 900 pounds per square inch. The particular temperature and. pressure employed will be correlated with the reaction time and ratio of benzene to ethylene to produce optimum results.

One important feature of the present inven-: tion resides in the use of a-substantial molar excess of benzene over ethylene or ethyl alcohol in the alkylation step, e. g., the molar ratio of benzene to ethylene may be from about 4:1 to about 20:1. The presence of high molar excesses of benzene promotes the formation of the more desirable monoethylbenzene and minimizes the production of polyethylbenzenes. Moreover, since alkylation of benzene with ethylene is a highly exothermic reaction, the presence ofv a large excess of benzene in the alkylation zone will assist in attaining adiabatic'operation because of the relatively high heat capacity of benzene. Another important advantage which results from the use or a large molar excess of benzene is found in the fact that recycling of the unconverted excess benzene to the alkylation. step, as hereinafter described in greater detail, provides a convenient method for recyrflug um convertedethylene to the alkylation step.

When ethblgalcoholend"?molar excess ofbenze ne ar'e charged directly to a catalytic "alkylation zone containing a solid phosphoric acid catalyst, substantially complete dehydration of the alcohollsobtained on a single pass through the catalyst zone but the conversion to ethylbenzene is often only about 25 to 35 mol per cent of -the available ethylene;

In th process of the present invention the ethyl alcohol is charged into the process stream t some intermediate point in the catalyst zone or into the inlet of one, of the last of a series of catalyst zones. The point of introduction of the ethyl alcohol is chosen so that the time of contact with the catalyst'will be suiificient to effect substantially complete dehydration of the alcohol. ing monoethy zene, ethylene, d water is subjected to fractionation. Theoverhead distillate from the fractionating column consisting principally of benzene, ethylene, and water is condensed and the water layer which is formed in the receiver is withdrawn. The temperature and pressure or The total reaction mixture comprisbenzene, polyethylbenzenes, benthe receiver are regulated to dissolve practically all of the ethylene in the liquid benzene. This stream of recycle benzene containing dissolved ethylene is then commingled with fresh benzene 5 and charged to the inlet of the reaction zone. The ethylene and molar excessof benzene are contacted with sufficient catalyst to-effect substantial completion of the alkylation of benzene with ethylene and at an intermediate point in the reaction zone ethyl alcohol is added. It will thus be seen that the remainder of the cataly alkylation zone in the direction of flow of the reactants also functions to dehydrate the added 'ethyl alcohol. Some alkylation will also occur in this portion of the reaction zone between the benzene and in situ generated ethylene, but a;

The invention thus avoids the inherent disadvantage of alkylating benzene with ethyl alco' hol directly and at the same time provides a unitary system wherein benzene and ethyl alcohol are the rawmaterials for the production of monoethylbenzene. The process has the further advantage that the introduction of. ethyl alcohol into the catalyst zone helps to maintain the solid phosphoric acid catalyst in a, proper state of hydration.

illustrates in greater detail the preferred method of practicing the present invention.

Fresh benzene is introduced through line! containing valve 2 to pump 3 which discharges through line A containing valve 5 to heater 6.

was hereinafter described is introduced from line 36 and commingled" with fresh benzene in line i. The catalyst chambers are preferably filledwith particles of a solid phosphoric acid catalyst of the type hereinbefore described. The eflluent stream from catalyst chamber 9 passes through line l2 and valve l3 to chamber ill. The eflluent' stream from chamber no is withdrawn through line i l and valve 15 and introduced into the final chamber of the series. 1

through line 48 containingvalve 49 to pump 50 which discharges through line 5i containing valve 52 to heater 53. The alcohol stream passes from heater 53 through line 5d containing valve 55 55 and is commingled in line i l with the eflluent reaction products from catalyst chamber l0.

. The total reaction mixture is withdrawn from chamber ll through line It containingvalve ll,

passes through heat exchanger l8," and is intro- '60 tionator 2 l In fractionator 2i; alkylatiorfproducts comprising monoethylbenzeneand the higher boiling polyethylbenzenesar' withdrawn through the 5s containing valve" 51 and may besubjected t further fractionation in a rerun column not shown.- The overhead product from frac'tionator 2i comprisingessentially benzene, water and ethylene passes through line 22 containing valve 23 to heat exchanger 24. The cooled overhead stream passes through line 25 and valve 26 to condenser 21. The resultant condensate and any noncondensable gases present are transferred through line 28 containing valve 29 to receiver 30. In the event that small amounts of inert or noncon- Reierence is now made to the drawing which Ethyl alcohol introduced to the system duced by means of line l9 and valve 20 to iraclar number of catalyst chambers.

densable gases are present the system,'these may be vented at this point through line 3! containing valve 32. Ordinarily, when an ethylene fraction is employed as the raw material charged to'the process substantial quantities of ethane as- 5 sociated with the ethylene will be vented from the system at this point. However, in the present invention since ethyl alcohol is the source of the ethylene reactant no substantial amount of ethane will be present. 1

In receiver the water resulting from the dehydration of alcohol will separate out as a lower layer which may be withdrawn through line 33 and valve 34. The temperature and pressure in receiver 30 are easily regulated so that substanl5 tially all of the ethylene present will dissolve in the excess benzene. This solution of ethylene in benzene is withdrawn through line 35 and a portion thereof is returned through valve 3t, pump 31, line 38 and valve 39 to the top of iractionator 20 20 as reflux. The remainder of the benzeneethylene stream is withdrawn through line 40 containing valve 41 and is recycled by means of I pump 42 through line 43 containing valve, heat exchanger 24,- line 45 containing valve d5, heat 25 exchanger l8, and line "containing valve ditto line I wherein it is commingled with fresh benzene and introduced into the inlet of catalyst zone 9.

Although the drawing depicts an alkylation 30 zone comprising three catalyst chambers wherein ethylialcohol is introduced into the third or last chamber of the series, it will be readily apparent that the invention is not limited'to any particucases it will be desirable to employ more than three chambers in series and in other cases fewer chambers may be employed. I I i It is within the scope of our invention to em- I ploy a single catalyst chamber with introduction 40 of ethyl alcohol at a point intermediate the inlet and exit ends thereof. If desired, the alkylating, catalyst may be disposed in separate beds in a single catalyst chamber with introduction of ethyl alcohol at an intermediate point between the 4 catalyst layers or beds.

An alternative method of operation'may be employed when the catalyst is disposed in a plurality of catalyst chambers as Shown in the drawing. In this alternative method oroperation valve I5 in line I4 is closed and the reaction productsfrom catalyst chamber ill are passed through line H and line 58 containingvalye 59 to line l6. Ethyl alcohol is introduced to chamber I I as previously describedand in addition a portion of the fresh benzene from line I is diverted through line 60 and valve 6i to line H and thence into chamber H. The eiiluent reaction mixture from chamber In and the reaction products from chamber H are commingled in line I6 and subso jected to fractionation as hereinbefore described. a

This alternative method of operation has the advantage that the monoethylbenzene present in the eiiluent reaction mixture from chamber I0 is not subjected to further contact with ethyl alco es hol or the ethylene produced therefrom in-chame ber ll. Thus the tendency toward-irr gation of polyethylene benzenes in chamber I i is avoidesL We claim aslour invention:

1, An alkylation process which comprises introducing an aromatic hydrocarbon and an olefin into the inlet end of an alkylation zone and therein alkylaltin! said aromatic hydrocarbon with said olefin, withdrawing reaction products from the outlet end of said alkylation zone, introduc- In certain 5 ing an alcohol at a point intermediatethe inlet and outlet of said zone and therein converting said alcohol towater and additional oleilnic reactants, and recycling said lastnamedoleiinic reactants to the inlet oisaidzone.

' 2; A process for the production of ethylbenzene which comprises introducing ethylene and products from an unconverted benzene fraction containing dissolved ethylene, recovering said alkylation products, and recycling said solutionof ethylene in benzene to the inlet of said zone.

3. A process for the production of mono-ethylbenzene whichcomprises' reacting benzene with ethylene analkylation' zone containing an alkylating and dehydrating catalyst; introducing ethyl alcohol to said zone at a point intermediate the inlet and outlet ends thereof andtherein dehydrating said alcohol 'to form ethylene and ,water'; withdrawing the reaction mixture from the outlet end of said zone; 'fractionating said mixture to separate alkylation roducts from a lower boiling fraction comprising unconverted benzene, ethylene, and water; subjecting said lower boiling fraction to condensation undentemv 'i perature and pressure conditions suitable for dis:

solving a substantialportion of said ethylene in said'beiizie; and recycling said solutionof ethylene in benzene to the inlet of said alkylation zone.

1. In a continuous process for the production of ethylbenz ene wherein benzene and ethylene are contacted with an alkylating' catalyst under alkylating conditions, the immovement,which comprises introducing ethyl'alcohol at a point intermediate the inlet and outlet ends or the re-' 1 action zone and therein converting said alcohol to ethylene and water, forming a solution of said .lastnamed ethylene in unconverted benzene, commingling said solution of ethylene in' benzene with additional iresh benzene,'and introducing said mixture into the inletend of said reaction zone. 5. The process of claim 2 wherein thecatalyst 'ccmprises a phosphoric acidalkylatin catalyst. 6. The process of claim 2 wherein said catalyst comprises a calcined composite of a catalytically I active acid of phosphorus and agenerally siliceous adsorbent.

7. The process of claim 2 wherein the catalyst cdmprises a solid phosphoric acid catalyst and i said alkylation zone is maintained at a temperature of from about fiell ltoaboutfifim'i. and a pressure of from about 300 to about 2000 pounds P quare inch. r

8. A process for the production of ethylbenzene which comprisesintroducing ethylene and a molar excess of benzene into the first of a plurality of serially disposed catalyst zones containing an alkylating and dehydrating catalyst and therein alkylating said benzene with said ethylene. intro I ducin'g ethyl alcohol into a subsequent zone in the series and therein dehydrating said alcohol to form ethylene and water, withdrawing the reaction mixture from the lastcatalyst zone'oi the series, iractionating said mixture to seperate alkylation products from an unconverted ben-' zene fraction containing dissolved ethylene. rc-

fad

covering said alkylation products, and. recycling said solution of ethylene in benzene'to the first chamber in said series.

9. A process for the production of ethylbenzene which comprises introducing ethylene and a molar excess of benzene into the inlet end of an,

-' alkylatlon zonecontaining an alkylating and dehydrating catalyst and therein'alkylating said benzene with said ethylene; contacting ethyl alcohol with a portion of the catalystin said zone and therein dehydrating said alcohol to form ethylene and water; withdrawing a mixture of alkylation and dehydration reaction products from said zone; fractionating said mixture to separate alkylation products from an unconverted benzene fraction containing dissolved ethylene; recovering said alkylation products;

and recycling said solution of ethylene in benzene to said catalyst zone. p I

10'. A process for the production of ethylbenzene which comprises introducing ethylene and a molar excess of benzene into a catalyst zone containing an alkylating and dehydrating catalyst. and therein alkylating said benzene with said ethylene; supplying ethyl alcohol and benzene to a portion of said catalyst zone andtherein dehydrating said ethyl alcohol to form ethylene and water; fractionating the reaction products from said catalyst zone; recovering alk'ylae tion products and water; and recycling a solution of ethylene in unconverted benzene to said catalyst zone 11. A process for the production of ethylbenzene which comprise introducing ethylene and a molar excess 'of benzene into the first of a plurality of serially disposed catalyst zones containing an alkylating and dehydrating catalyst and therein alkylating said benzene With said ethylene; withdrawing the alkylation reaction mixture from an intermediate zone in the series; introducing ethyl alcohol and benzene into the next subsequent zone in the series and therein dehydrating said alcohol to form ethylene and water; commingling the alkylation and dehydration reaction products; fractionating the mixis alkylated with the olefin in the presence of a catalyst comprising silica and alumina. a

, 13. The process as defined in claim 2 further characterized in that said catalyst comprises silica and alumina.

'14. The process as defined in claim- 1 further v characterized in that said aromatic hydrocarbon is 'alkylated with the olefin in the presence of a phosphoric acid .catalyst. 

